The present invention relates to a method of manufacturing side glass for a vacuum fluorescent display (VFD), and more particularly, to a method of manufacturing the VFD more efficiently by manufacturing the side glass of the VFD with a simple and convenient process.
The vacuum fluorescent display (VFD) is a well known flat display device which displays an image on its screen by emitting hot electrons from its cathode made of a filament, controlling the movement of the hot electrons with grids, and irradiating the hot electrons to an anode plate on which fluorescent materials are coated.
A vacuum case, in which at least one side is transparent, is mounted on the VFD's external side, and an evacuation tube is conventionally formed on the vacuum case to extract air or gas from the vacuum case. Specifically, the vacuum case includes a base glass in which a circuit board is formed, a side glass which is mounted on the base glass, and a front glass which is mounted on the side glass. Conventionally, the evacuation tube is formed on the side glass, and after extracting gas or air from the vacuum case through the evacuation tube, the end of the evacuation tube is sealed.
However, the conventional VFD with the vacuum case has several disadvantages. That is, the evacuation tube is easily destroyed by external impact and the external appearance of the VFD is not aesthetically pleasing because part of the evacuation tube is exposed to the outside of the side glass.
Recently, VFD's have been formed with evacuation holes formed on the base glass to extract the gas or air from vacuum case instead of using the evacuation tube formed on the side glass. In these systems, after extracting the gas or air from the vacuum case through the evacuation hole with an evacuation device, such as a pump, the evacuation hole is sealed with a seal cap to maintain the vacuum formed in the vacuum case.
The VFD having the evacuation hole instead of the evacuation tube will be described with reference to FIG. 6. As shown in FIG. 6, the vacuum case of the VFD includes a base glass 1 in which the evacuation hole 10a is formed, a side glass 3 which is mounted on the edges of the base glass 1, and a front glass 5 which is mounted on the side glass 3. The base, side and the front glasses 1, 3, 5 are adhered to each other with a sealing frit (S-Frit). The seal cap 7 is attached beneath the base glass 1 to seal the evacuation hole 10a after extracting the gas or air from the vacuum case. The base glass 1 is produced by several processes including a circuit masking process. The side glass 3, which is made of four pieces of glass, is conventionally produced by the following process. Namely, the method for manufacturing the side glass 3 includes the steps of (1) cutting four pieces of glass at predetermined lengths, (2) cleaning the four pieces of glass, (3) adhering the four pieces of glass together in the shape of a rectangular box (side glass) with mounting frits (M-Frit), (4) coating a sealing frit on the upper side of the side glass, and (5) plasticizing the sealing frit and examining the side glass.
However, by adhering the four pieces of glass, the manufacturing process of the VFD is more complex. Furthermore, the four pieces of glass must be scribed and produced to have exactly same lengths with the lengths of the VFD. In addition, a large amount of the mounting frit is required to adhere the four pieces of glass, which increases the cost of manufacturing the VFD.